The development tendency of the optical transport technology presents the characteristics of a higher single-channel rate (for example, single-channel 400 G/1 T transport), a higher spectrum efficiency and a higher-order modulation format, so that it is still the most explicit and the most important direction of optical transport development to continue to improve the rate. The high-rate transport faces many restrictions, which are mainly in two aspects: on one hand, the optical transport technology develops towards high-spectrum efficiency convergence transport and high-rate service interface transport, and if the spectrum efficiency cannot be improved continuously, then it makes little sense to convergent from a low-rate to a high-rate and then perform transport; however, since there may still be a high-rate Ethernet interface at a client side, the problem of the transport of a high-rate interface still needs to be considered, and 400 G would be a critical point of the spectrum efficiency limit; on the other hand, the optical transmission technology develops towards a long distance (long span segment and multi-span segment), although the optical signal-noise ratio (OSNR) of a system can be improved by way of using low-loss optical fibre and a low-noise amplifier, reducing span segment spacing, etc., the improvement is limited and it is difficult to make a major breakthrough, and it is also difficult to be implemented in engineering.
With an increasing demand for the bandwidth of a bearing network, the beyond 100 G technology becomes a solution for meeting the growing demand for bandwidth; above 100 G, no matter 400 G or 1 T, the traditional wavelength division multiplexing (WDM) with a 50 GHz fixed grid cannot provide sufficient spectrum width to realize the beyond 100 G technology. Due to the defects of the fixed grids, the requirement for wider flexible grids is proposed.
In the related art, beyond 100 G multi-rate mixed transmission and beyond 100 G modulation code flexibility lead to different channel bandwidth demands, and if each channel is customized with an appropriate bandwidth, full use of the system bandwidths can be achieved, thereby generating a flexible grid system. On the basis of a demand for an ultra high-rate WDM system due to the continuously increasing of the bandwidth demand, a demand for the flexible grid technology is introduced. However, many problems, such as how to perform frequency spectrum planning and administration effectively and the compatibility with the existing systems, are to be resolved.
In view of the problem of how to map and multiplex data effectively after a flexible grid is introduce into the related art, no effective solution has been proposed so far.